Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
During operation of a wind turbine, the wind turbine is subjected to thrust due to the interaction of wind with the rotor blades of the wind turbine. Excessive thrust may cause damage to the wind turbine. For example, thrust may cause the tower of the wind turbine to bend, causing fatigue loading of the structure. Excessive thrust may cause the tower to bend past a limiting point, causing failure of the tower and the wind turbine in general.
Known methods for controlling thrust in order to prevent damage or failure involve estimating the thrust by measuring the actual power produced by the wind turbine. This estimate of the thrust may be monitored, and if the estimated thrust reaches a predetermined peak value, the pitch of the rotor blades may be adjusted to reduce the estimated thrust. However, this thrust estimate may be influenced by various extraneous factors, such as variations in blade geometry, icing, fouling, and/or pitching errors, and may thus generally not be an accurate measurement of thrust.
Accordingly, an improved method and apparatus for controlling wind turbine thrust would be desired in the art. For example, a method and apparatus for more accurately controlling wind turbine thrust would be advantageous.